1. Field of the Invention
The present invention relates to a protective film for a flat panel display (FPD) such as a plasma display panel (PDP), a plasma addressed liquid crystal display (PALC), and the like and an FPD in which the protective film is used, a vapor deposition material suitable for forming a protective film for FPD and its production method, and a device for manufacturing an FPD protective film.
2. Description of Related Art
During the past several years, there has been considerable activity in the research and development as well as practical application of liquid crystal displays (LCD) and various other types of flat displays, and production of these displays is also increasing rapidly. There has recently also been growing activity in the development and practical application of color plasma display panels (PDP). PDP are easily applied to large screens, and are the easiest way to achieve large-screen wall-mounted televisions for Hi-Vision applications, and prototypes of PDP offering a diagonal size of 40 inches have already been developed. In the case of FPD, which include these PDP, the glass dielectric layer is directly exposed to electrical discharge, and the surface of the dielectric layer changes due to sputtering of ion collisions resulting in a rise in the discharge starting voltage. Consequently, various oxides having a high heat of sublimation have been used as protective films.
In the past, known examples of depositing this protective film included methods involving the formation of an FPD protective film using a vacuum process such as electron beam vapor deposition, sputtering and ion plating. In the case of electron beam vapor deposition and ion plating, the vapor deposition material serving as the raw material for forming the protective film, and the FPD on which the protective film is formed, are placed in a vacuum container, the vapor deposition material is heated under a high vacuum, or evaporated using an electron beam or plasma, and the vapor is agglutinated in the form of a thin film on the surface of the FPD.
On the other hand, since a PDP protective film is in direct contact with the discharge space, it serves as the key material for fulfilling the most important role for discharge characteristics, and an MgO film was used in the past due to its high secondary electron discharge capabilities and superior sputtering resistance, light transmission and insulating properties.
However, if this MgO film is exposed to the atmosphere during the course of processing, it deteriorates easily as a result of reacting with CO2 and H2O. Therefore, it is known that degassing exhaust treatment over a long period of time while heating in a vacuum after sealing the film on the panel is required in order to obtain the inherent characteristics of MgO (see, for example, Sato, ed., Current Plasma Display Production Technology (Press Journal Co., Ltd.): p. 118-123 and p. 291-295 (1997)). According to this, impurity gases such as H2O, H2, O2, CO, CO2 and N2 have a detrimental effect on PDP discharge characteristics and composite materials in the panel, and contamination by CO2 in particular can worsen panel characteristics beyond recovery.
Consequently, the coating of the MgO surface with another material having low moisture permeability has been proposed in order to prevent deterioration of MgO (Japanese Unexamined Patent Application, First Publication No. 10-149767, W. T. Lee et al.: xe2x80x9cLaF3 coated MgO protecting layer in AC-Plasma Display Panelsxe2x80x9d, IDW ""99, p. 72-75).
The above Japanese Unexamined Patent Application, First Publication No. 10-149767 proposes a PDP production method consisting of forming a protective film followed by temporarily forming a protective film having a low moisture permeability on this protective film, and then removing that temporary protective film. According to this method, during production of the PDP, since the surface of the protective film is protected by a temporary protective film, a deteriorated layer is not formed on the surface of the protective film. As a result, in addition to being able to obtain a protective film with satisfactory discharge characteristics, thermal decomposition treatment of a deteriorated layer on the protective film is not required.
In addition, in the above reference of W. T. Lee et al, together with suppressing deterioration of the MgO protective film by coating LaF3 having low moisture permeability onto an MgO protective film, it is proposed that higher secondary electron discharge characteristics and lower discharge characteristics can be realized.
However, in the production methods described in the above-mentioned Japanese Unexamined Patent Application, First Publication No. 10-149767 and the reference of W. T. Lee et al. of the prior art, it is difficult to conform the temporary protective film with the protective film when forming the temporary protective film, and there are cases in which cracks may form in the temporary protective film or the temporary protective film may peel off, thus making the effect of the temporary protective for preventing deterioration of the protective film inadequate. In order to improve this, although a method was considered in which a temporary protective film is laminated in a thick layer onto a protective film, in this method, there was the problem of a large amount of impurities (decomposition products of the temporary protective film) being formed during removal of the temporary protective film.
Moreover, in the above reference of W. T. Lee et al., 5-90 nm of LaF3 are laminated onto MgO and in this double layer structure, when the LaF3 of the upper layer film is removed by sputtering, there was the problem of an adequate lifetime being unable to be obtained due to sudden changes in the discharge voltage
In addition, alkaline earth metal oxides are used as vapor deposition materials that serve as the raw materials for forming a superior protective film as described above.
However, similar to MgO films, if these alkaline earth metal oxides are exposed to the atmosphere before being used as vapor deposition materials, they are easily deteriorated as a result of reacting with CO2 and H2O. Consequently, it is known that, after placing vapor deposition materials comprised of alkaline earth metal oxides in a vacuum container, degassing exhaust treatment for a long period of time while heating in a vacuum is required. Namely, if degassing exhaust treatment is not performed for a comparative long period of time, impurity gases such as H2O, H2, O2, CO, CO2 and N2 generated in large amounts from the deteriorated surface of the vapor deposition material cause problems in the characteristics of the resulting protective film.
In addition, as an example of a manufacturing device for producing a protective film as described above, a manufacturing device for FPD protective films is disclosed comprising coupling a loading chamber that loads substrate onto a line, a heating chamber that heats the substrates, a film formation chamber in which a film body is formed on one surface of the substrates, a cooling chamber that cools the substrates, and an unloading chamber that unloads substrates from the line, without exposing them to the atmosphere (inline system), whereby a protective film is formed by electron beam vapor deposition and so forth at a predetermined region on the substrates (see, for example, Ulvac Technical Journal, No. 46, pp. 8-13 (1997), 7th Fine Process Technology Japan ""97 Seminar preliminary collection of papers, D5, pp. 35-42 (1997)). In a manufacturing device for FPD protective film composed in this manner, since the process is carried out from loading to unloading of substrates without exposing the process to the atmosphere, improved productivity and conservation of space can be realized.
On the other hand, as examples of an apparatus for treating materials with a gaseous fluoridation agent, a dry etching apparatus that performs treatment with a mixed gas of HF and H2O for removing silicon oxide films on silicon wafers (see, for example, Japanese Patent Publication No. 2741546, Published Japanese Translation No. 6-26206 of PCT International Publication, Monthly Semiconductor World, [3], pp. 121-123 (1988), the Excalibur paper phase cleaning system described in the catalog of MFSI Co., Ltd., and the Falcon HF reduced pressure gas phase etching system described in the catalog of ASM Japan Co., Ltd.), and a surface treatment method and its apparatus for surface treatment of polyolefin resin molded products, polypropylene resin, carbon black and plastic molded products with a mixed gas containing fluorine, are disclosed (see Japanese Unexamined Patent Application, First Publication No. 10-101830, Japanese Unexamined Patent Application, First Publication No. 10-204195, Japanese Unexamined Patent Application, First Publication No. 940881 and Japanese Unexamined Patent Application, First Publication No. 10-182861).
In the above-mentioned dry etching apparatus for silicon wafers, dynamic systems, in which after performing treatment by introducing a gaseous fluoridation agent at a constant concentration into the system at nearly atmospheric pressure, inert gas is introduced followed by removal of residual gas, and closed systems, in which treatment is performed by introducing a gaseous fluoridation agent at a constant pressure into the reaction under a vacuum, returning the system to a vacuum, and after removing the residual gaseous fluoridation agent, inert gas is introduced and the system is returned to atmospheric pressure, have been proposed. These apparatuses allow selective etching of various types of silicon oxide films on silicon wafers by optimizing the mixing ratio of HF and H2O, HF concentration or HF partial pressure, reaction temperature, reaction time and so forth. Moreover, this dry etching apparatus enables particle generation to be reduced in comparison with wet etching. In addition, in the method and its apparatus for surface treatment of polyolefin molded products, polypropylene resin, carbon black and plastic molded products, etc. with a mixed gas containing fluorine, by making the surface of the treated material hydrophilic, dispersivity in aqueous solutions as well as coating, adhesion and other characteristics can be improved.
However, in the above manufacturing device for FPD protective film of the prior art, there is the risk of the protective film easily deteriorating as a result of reacting with CO2 and H2O if the protective film is exposed to the atmosphere after forming. In order to prevent this deterioration of the protective film, a method and apparatus have been considered that contact the protective film with a gaseous fluoridation agent to form a fluoride film on the surface of the protective film. However, in this fluorinating treatment method and apparatus, since FPD substrates are typically formed from glass, the substrate easily corrodes and becomes clouded, namely there was the problem of the FPD display surface and outgoing circuits around the FPD protective film ending up being clouded.
On the other hand, a treatment apparatus and method are disclosed composed such that substrates are placed nearly level in a chamber isolated from the surrounding environment, and regulatory gas containing a reactive gas is fed into the chamber to regulate the substrates (Published Japanese Translation No. 10-512100 of PCT International Publication). In this apparatus, a high-pressure gas inlet region into which regulatory gas is introduced is formed in the upper portion of the chamber, and a low-pressure regulation chamber that houses substrates in the center of the chamber is formed that regulates the substrates with the above regulatory gas. The above gas inlet region and regulation chamber are partitioned by a first pressure bias means comprised of a porous plate. In addition, a second pressure bias means is provided in the lower portion of the chamber that directs the flow of regulatory gas on the surface of the substrates to the outside and causes it to move in the direction of the outer periphery of the substrates, while an exhaust outlet is provided around or in the center of the lower end of the above substrates that discharges the above regulatory gas. This exhaust outlet is connected to an exhaust means.
In the treatment apparatus composed in this manner, high-pressure regulatory gas that has entered the chamber from the gas inlet portion is reduced to low pressure by the first pressure bias means and becomes a viscous flow. After chemically reacting with the substrate surface, it uniformly flows to the outside of the substrate surface and is discharged through an exhaust outlet around or in the center of the lower end. As a result, even in the above treatment apparatus, there was the problem that, although corrosion of the bottom surface of the substrate can be prevented, if regulatory gas makes contact with the portion at which the FPD protective film is not formed on the ends of the substrate surface in the same manner as described above, namely the outgoing circuits, and gaseous fluoridation agent is contained in the regulatory gas, the ends of the substrate surface end up being corroded.
In consideration of the above problems, a first object of the present invention is to provide a vapor deposition material for an FPD protective film and its production method that enables the degassing exhaust treatment time immediately after placing in a container to be shortened.
A second object of the present invention is to provide a vapor deposition material for an FPD protective film and its production process that enables the formation of a film having stable and uniform characteristics.
A third object of the present invention is to provide an FPD protective film that prevents decreases in adhesion and conformity with a substrate (dielectric layer) while also preventing decreases in electrical insulating properties.
A fourth object of the present invention is to provide an FPD protective film that improves the environmental resistance of a film body, namely inhibits or suppresses MgO and so forth from decomposing into MgCO3, Mg(OH)2 and other substances harmful to FPD by a fluoride layer inhibiting or suppressing the reaction of MgO and so forth in the film body with CO2 gas and H2O gas in the atmosphere during the FPD production process.
A fifth object of the present invention is to provide an FPD using a protective film that significantly reduces the number of production steps.
A sixth object of the present invention is to provide a manufacturing device for FPD protective film that prevents corrosion of the display surface or outgoing circuits around the film body of a substrate by a gaseous fluoridation agent during formation of a fluoride layer.
A seventh object of the present invention is to provide a manufacturing device for FPD protective film that continuously carries out formation of a film body and fluoride layer.
An eighth object of the present invention is to provide a manufacturing device for FPD protective film that prevents deterioration in the FPD production process caused by MgO in the film body reacting with CO2 gas and H2O gas in the atmosphere.
In order to achieve the above objects, the present invention provides a vapor deposition material for FPD protective film that is formed from a polycrystalline body, a sintered body, or single crystal having a surface covered with a fluoride layer.
Consequently, since the surface of the polycrystalline body, sintered body, or single crystal is covered with a fluoride layer, the polycrystalline body, sintered body, or single crystal hardly reacts at all with CO2 gas or H2O gas in the atmosphere even this vapor deposition material is exposed to the atmosphere for a long period of time. As a result, the amount of harmful substances generated after placing this vapor deposition material in a vacuum deposition container is suppressed to below that of the prior art, and the amount of time for degassing exhaust treatment that has conventionally been carried out to remove these harmful substances can be shortened, or the gas treatment step can be omitted, thereby making it possible to reduce FPD production costs to below the level of the prior art.
In addition, the above polycrystalline body, sintered body, or single crystal may be formed from one type or two or more types of oxides selected from MgO, CaO, SrO, BaO, alkaline earth composite oxides, rare earth oxides, and composite oxides of alkaline earth oxides and rare earth oxides.
In addition, the above fluoride layer may be obtained by reacting a fluoridation agent with one type or two or more types of oxides selected from MgO, CaO, SrO, BaO, alkaline earth composite oxides, rare earth oxides, and composite oxides of alkaline earth oxides and rare earth oxides.
As a result of employing these constitutions, since the vapor deposition material evaporates without generating impurity gases such as H2O, H2, O2, CO, CO2 and N2 during formation of a protective film on an FPD by electron beam vapor deposition or ion plating and so forth, high-speed and stable film formation is possible, the fineness of the film is improved, and a uniform film can be formed having stable characteristics.
Moreover, the present invention provides a production method of a vapor deposition material for an FPD protective film comprising a step in which one type or two or more types of polycrystalline body, sintered body, or single crystal selected from MgO, CaO, SrO, BaO, alkaline earth composite oxides, rare earth oxides, and composite oxides of alkaline earth oxides and rare earth oxides is formed, and a step in which a fluoride layer is formed on the surface of the above polycrystalline body, sintered body, or single crystal by surface treatment of the above polycrystalline body, sintered body, or single crystal with a fluoridation agent.
Consequently, a vapor deposition material may be obtained comparatively easily that hardly reacts at all with CO2 gas and H2O gas in the atmosphere even if exposed to the atmosphere for a long period of time.
In addition, one type or two or more types of fluoridation agents may be selected from fluorine gas, hydrogen fluoride gas, BF3, SbF4 and SF4.
Consequently, a fluoride layer may be formed comparatively easily on the surface of a polycrystalline body, sintered body, or single crystal.
In addition, an FPD may be formed using this protective film by forming a protective film using the above vapor deposition material for an FPD protective film, or a vapor deposition material obtained from the above production method of a vapor deposition material for an FPD protective film.
Consequently, FPD may be produced inexpensively as a result of being able to significantly reduce the number of FPD production steps.
Moreover, the present invention provides an FPD protective film equipped with a film body formed from one type of two or more types of oxides selected from MgO, CaO, SrO, BaO, alkaline earth composite oxides, rare earth oxides, and composite oxides of alkaline earth oxides and rare earth oxides on the surface of a substrate, and a fluoride layer formed on the surface of the above film body, wherein the above film body is an aggregate of a plurality of columnar crystallites densely standing on the surface of the above substrate, and the above fluoride layer is respectively formed on the peripheral side surfaces and apices of the above plurality of columnar crystallites.
Consequently, since a plurality of columnar crystallites that compose a film body are each covered with a fluoride film, even if a protective film composed of this film body and fluoride film is exposed to the atmosphere for a long period of time in the FPD production process, the MgO and so forth in the film body hardly reacts at all with CO2 gas and H2O gas in the atmosphere. As a result, since there is hardly any decomposition of MgO and so forth in the film body into MgCO3, Mg(OH)2 or other substances for which there is the risk of impairing the function of the FPD, the environmental resistance of the film body is improved. In addition, since the film body of the protective film that has a coefficient of thermal expansion which is approximately equal to that of the substrate is adhered to the substrate, the protective film does not peel from the substrate due to thermal cycling, and the adhesion and conformity of the protective film to the substrate are extremely satisfactory.
In addition, the above fluoride layer may be MOXFY (wherein, M is selected from one type of two or more types of Mg, Ca, Sr, Ba, alkaline earth compound metal, rare earth metal and a compound metal of an alkaline earth metal and rare earth metal, and 0xe2x89xa6X less than 2 and 0 less than Yxe2x89xa64).
In addition, the above fluoride layer may be formed from a reaction between a fluoridation agent and one type or two or more types of oxides selected from MgO, CaO, SrO, BaO, alkaline earth composite oxides, rare earth oxides, and composite oxides of alkaline earth oxides and rare earth oxides.
In addition, the above fluoridation agent may be one type or two or more types selected from fluorine gas, hydrogen fluoride gas, BF3, SbF4 and SF4.
Consequently, since MgO and so forth in the film body does not decompose into MgCO3, Mg(OH)2 or other substances harmful to the function of the FPD, the amount of time for degassing exhaust treatment that has conventionally been carried out to remove the MgCO3, Mg(OH)2 or other harmful substances in a later step can be shortened, or the gas treatment step can be omitted, thereby making it possible to reduce FPD production costs.
In addition, the ratio (y/x) of the thickness of the above fluoride layer (y) to the diameter of the above columnar crystallites (x) may be from 0.001 to 0.2.
Here, the xe2x80x9cdiameter of columnar crystallitesxe2x80x9d refers to diameter xe2x80x9cxxe2x80x9d in the case the cross-section of columnar crystallites 14a is circular as shown in FIG. 9, or length xe2x80x9cxxe2x80x9d from the apex to the opposite side in the case the cross-section of columnar crystallites 14a is triangular as shown in FIG. 10. In addition, xe2x80x9ccolumnarxe2x80x9d is not limited to that having a circular or triangular shape as mentioned above, but rather includes that having a polygonal shape such as a quadrangle, pentagon or hexagon, or that having an elliptical shape.
As a result of employing these, the above effects can be demonstrated more remarkably.
In addition, an FPD may also be produced using the above FPD protective film.
Consequently, since the number of FPD production steps can be reduced considerably, FPD can be produced inexpensively.
Moreover, the present invention provides a manufacturing device for FPD protective film equipped with a film formation means that forms a film body on one side of a substrate, and a layer formation means that forms a fluoride layer on the surface of the above film body; wherein, the above layer formation means has a layer formation chamber that houses a substrate on which the above film body is formed, a gas supply mechanism that forms a fluoride layer on the surface of the above film body by supplying a fluoridation agent towards the above substrate in the above layer formation chamber, and a substrate heating means that heats the above substrate provided in the above layer formation chamber.
Consequently, fluoridation agent is supplied towards the surface of a film body formed on one side of a substrate by a gas supply means simultaneous to heating the substrate. As a result, together with being able to form a fluoride layer on one side of the substrate, reactivity between the other side of the substrate and the outgoing circuits around the film body (ends of the substrate) with the fluoridation agent is suppressed. Namely, since the selective reactivity of the substrate and film body with respect to the fluoridation agent is improved by heating the substrate with a substrate heating means, corrosion of the substrate by the fluoridation agent can be prevented.
In addition, the above film formation means may also have a film formation chamber that houses the above substrate, and a substrate heating means that heats the above substrate in the above film formation chamber.
In addition, the above film body may be formed using one type or two or more types of oxides selected from alkaline earth oxides, rare earth oxides and composite oxides of alkaline earth oxides and rare earth oxides.
In addition, the above film formation means may be composed using any of electron beam vapor deposition, sputtering, ion plating, screen printing, spin coating or spray coating, the above film body is formed on one surface of the above substrate, and the above substrate may be transferred from the above film formation means to the above layer formation means by a substrate transfer means.
Consequently, if a film body is formed on one side of a substrate by a film formation means, and this substrate is transferred to a layer formation means by a substrate transfer means, formation of the film body and fluoride layer can be carried out continuously.
In addition, the above substrate transfer means may be composed so that the above substrate is transferred from the above film formation means to the above layer formation means without being exposed to the atmosphere.
Consequently, decomposition of MgO and so forth in the film body into MgCO3, Mg(OH)2 and other substances harmful to FPD due to reacting with CO2 gas and H2O gas in the atmosphere can be prevented.
In addition, the above film formation means may bake the above substrate on which the above film body is formed on one surface in the air, and the above layer formation means may form the above fluoride layer on the surface of the film body of this baked substrate.
Consequently, since the substrate is baked in the atmosphere after a film body has been formed on one side of the substrate by a film formation means but before a fluoride layer is formed on the surface of the film body, decomposition of MgO and so forth in the film body into MgCO3, Mg(OH)2 and other substances harmful to FPD due to reacting with CO2 gas and H2O gas in the atmosphere can be prevented.
Moreover, the present invention provides a manufacturing device for FPD protective film equipped with a film formation means that forms a film body on one side of a substrate, and a layer formation means that forms a fluoride layer on the surface of the above film body; wherein, the above layer formation means has a layer formation chamber that houses a substrate on which the above film body is formed, a treatment dome provided inside the above layer formation chamber that is pressed against one side of the above substrate while maintaining an airtight state, and a gas supply mechanism that forms a fluoride layer on the surface of the above film body by supplying a fluoridation agent inside the above treatment dome.
Consequently, a substrate on which a film body is formed on one side is housed in a layer formation chamber, and a treatment dome is pressed against one side of the substrate. Fluoridation agent is then supplied inside the treatment dome while in this state to form a fluoride film on the surface of the film body. As a result, since fluoridation agent does not make contact with the other side of the substrate or outgoing circuits around the film body, corrosion of the substrate by the fluoridation agent can be prevented.
In addition, the above film body may be formed using one type or two or more types of oxides selected from alkaline earth oxides, rare earth oxides and composite oxides of alkaline earth oxides and rare earth oxides.
In addition, the above film formation means may be composed using any of electron beam vapor deposition, sputtering, ion plating, screen printing, spin coating or spray coating, the above film body is formed on one surface of the above substrate, and the above substrate may be transferred from the above film formation means to the above layer formation means by a substrate transfer means.
Consequently, if a film body is formed on one side of a substrate by a film formation means, and this substrate is transferred to a layer formation means by a substrate transfer means, formation of the film body and fluoride layer can be carried out continuously.
In addition, the above substrate transfer means may be composed so that the above substrate is transferred from the above film formation means to the above layer formation means without being exposed to the atmosphere.
Consequently, decomposition of MgO and so forth in the film body into MgCO3, Mg(OH)2 and other substances harmful to FPD due to reacting with CO2 gas and H2O gas in the atmosphere can be prevented.
In addition, the above film formation means may bake the above substrate on which the above film body is formed on one surface in the air, and the above layer formation means may form the above fluoride layer on the surface of the film body of this baked substrate.
Consequently, since the substrate is baked in the atmosphere after a film body has been formed on one side of the substrate by a film formation means but before a fluoride layer is formed on the surface of the film body, decomposition of MgO and so forth in the film body into MgCO3, Mg(OH)2 and other substances harmful to FPD due to reacting with CO2 gas and H2O gas in the atmosphere can be prevented.